Conventionally, as a laminate film to be used for food packaging applications and having gas barrier properties, there are known films formed by laminating a thin film of metal such as aluminum on a thin film of inorganic oxide such as silicon oxide or aluminum oxide (hereinafter, referred to as inorganic layer) or on a surface of a plastic film. However, in industrial uses for solar cells, electronic paper, organic EL elements, semiconductor elements, etc., the above laminate films are insufficient in gas barrier properties, and it is required to further improve the gas barrier properties.
A method for laminating an inorganic layer and a thin film containing an organic material (hereinafter, referred to as organic layer) on a plastic film is supposed to be one of means for improving the gas barrier properties.
The organic layer is formed by a common coating method, but it is also possible to be formed by employing a vapor deposition method. Vapor deposition methods can be broadly divided into physical vapor deposition methods such as a vacuum vapor deposition method, a sputtering method and an ion plating method, and chemical vapor deposition methods such as PECVD (plasma enhanced CVD), and usually, a physical vapor deposition is employed.
When a physical vapor deposition method is employed, gas barrier properties can be obtained to a certain extent, and even when a substance is vapor-deposited on a further wide area, the film thickness can be made even. In addition, when a physical vapor deposition method is employed, vacuum film formation of organic substance and inorganic substance is continuously carried out so that the formation efficiency such as cost reduction and shortening of film formation time can be improved.
As a laminate film including an inorganic layer and an organic layer, there are known laminate films formed by laminating an inorganic layer and an organic layer containing melamine (e.g., reference to Patent Documents 1 and 2). In the patent documents above, methods are proposed for laminating an inorganic layer on a plastic film and vapor-depositing an organic layer on the inorganic layer by vacuum vapor deposition method. The organic layer contains triazine compounds (e.g., melamine salts such as melamine, melem, melam, ammeline, ammelide, cyanuric acid, 2-ureidomelamine and melamine cyanurate, and melamines functionalized by polymerizable group such as acrylate, epoxy, or vinyl ether) or a mixture of the above triazine compounds.
Incidentally, in the case of using the laminate film for packaging uses, it is required not only to be excellent in gas barrier properties but also to be excellent in adhesive force between the organic layer and the inorganic layer (hereinafter, referred to as adhesive force). However, although having gas barrier properties, the laminate films produced by the methods described in Patent Documents 1 and 2 have a problem that the adhesive force is weak.